1. Field of the Invention
The present invention relates to an ultrasonic diagnostic apparatus, and particularly to an ultrasonic diagnostic apparatus which utilizes Doppler effect of ultrasonic wave to diagnose kineticism of moving bodies in side the body such as blood and kineticism of tissues.
2. Description of the Background Art
In circulatory organ routine checkup examinations, decisions of abnormal systolic/diastolic function or decisions of abnormal valve disorders in a heart are performed by utilizing blood flow signals, and further evaluations of systolic/diastolic function in left ventricular cardiac muscle or abnormal local wall movements are performed by utilizing wall (tissue) signals. In general, the diagnosis is carried out by switching between a blood flow analysis mode (PWD mode) for evaluating only blood flow and a tissue analysis mode (TDI-PW mode) for evaluating only the wall (tissue) signals in case of effecting the former and the latter decisions. In this case, when the frequency detected exceeds the repetition frequency (±½ PRF), the waveform which is folded back is obtained as shown in FIG. 1. As described above, it is necessary for an examiner to properly set a pulse repetition frequency (rate frequency) or a baseline position in response to a blood velocity (tissue velocity) in order to cause a waveform which has small amplitudes as shown in FIG. 2B or which is folded back as shown in FIG. 2C to be the waveform as shown in FIG. 2A. For this reason, the adjustment required takes a much operation time, and further it is a remarkable burden on the examiner.
In this respect, recently in a Doppler mode, there has been disclosed a technology for automatically adjusting the velocity range and the baseline position on an apparatus side in order that blood flow signals and tissue signals having various velocities and directions are displayed so as to facilitate visualization always without being folded back (see Jpn. Pat. Appln. KOKAI Publication No. 8-308843). In the technology, a signal existence region is detected with regard to a range in which detectable frequencies exist, whereby the repetition frequency and the baseline position are automatically set. As a result, the burden on an examiner can be reduced, whereby a time required for diagnosis can be remarkably shortened. Although there are a variety of algorithms with respect to the automatic adjustment, when the function therefor is utilized, complications in the operations during the routine examination can be remarkably improved, whereby the examination efficiency is improved. In the automatic adjustment method, when a user pushes once the button provided on the panel of an apparatus, it is usually possible to obtain the Doppler waveform adjusted automatically.
However, the existing Doppler automatic adjustment function is a mere function for analyzing the signals received to adjust the velocity range (repetition frequency), the baseline position and the like in order to exclude a folded back phenomenon of the Doppler signals received. Accordingly, the existing Doppler automatic adjustment function does not include a function for changing the transmission/reception condition for obtaining a further optimum reception signal with respect to the received signals.
Moreover, the existing Doppler automatic adjustment function does not include even a function for deciding whether the received signal is a blood flow signal or a tissue signal. Accordingly, there is neither a function for providing a method for transmitting/receiving the optimum blood flow signal together with the existing automatic adjustment function when the signal received is decided to be a blood flow signal, nor a function for providing a method for transmitting/receiving the optimum tissue signal together with the existing automatic adjustment function when the signal received is decided to be a tissue signal.